Multi-speed transmission having stacked planetary gear sets

ABSTRACT

A transmission is has an input member, an output member, two stacked planetary gear sets, a third planetary gear set, a plurality of coupling members and a plurality of torque transmitting devices. The stacked planetary gear sets have a first, second, third, fourth and fifth member and the third planetary gear set has a first, second and third member. The torque transmitting devices include clutches and brakes.

FIELD

The invention relates generally to a multiple speed transmission havinga plurality of planetary gear sets and a plurality of torquetransmitting devices and more particularly to a transmission havingeight or more speeds, four planetary gear sets of which two are stackedand a plurality of torque transmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of frictionclutches, planetary gear arrangements and fixed interconnections toachieve a plurality of gear ratios. The number and physical arrangementof the planetary gear sets, generally, are dictated by packaging, costand desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

A transmission is provided having an input member, an output member,four planetary gear sets of which two are stacked to form a stackedplanetary gear set arrangement, a plurality of coupling members and aplurality of torque transmitting devices. The torque transmittingdevices are for example clutches and brakes.

In an aspect of the present invention, a first and a second set ofplanetary gear sets are provided having a sun gear, a carrier member forrotatably supporting a plurality of pinion gears and a ring gear member.The stacked planetary gear set arrangement has a sun gear, a firstcarrier member for rotatably supporting a first plurality of piniongears, a second carrier member for rotatably supporting a secondplurality of pinion gears, a ring gear and a common member.

In another embodiment of the present invention, an interconnectingmember continuously interconnects the ring gear of the stacked planetarygear set arrangement with the sun gear of the planetary gear set.

In another embodiment of the present invention, a first interconnectingmember continuously interconnects the carrier member of the firstplanetary gear set with the carrier member of the second planetary gearset.

In another embodiment of the present invention, a second interconnectingmember continuously interconnects the ring gear of the first planetarygear set with the ring gear of the second planetary gear set.

In another embodiment of the present invention, a third interconnectingmember continuously interconnects the sun gear of the first planetarygear set with the second carrier member of the stacked planetary gearset arrangement.

In another embodiment of the present invention, a fourth interconnectingmember continuously interconnects the first carrier member of thestacked planetary gear set arrangement with the second carrier member ofthe stacked planetary gear set arrangement.

In still another embodiment of the present invention, a first torquetransmitting mechanism is provided that is selectively engageable tointerconnect the ring gear of the first planetary gear set with theinput member.

In still another embodiment of the present invention, a second torquetransmitting mechanism is provided that is selectively engageable tointerconnect the sun gear of the stacked planetary gear set arrangementwith the input member.

In still another embodiment of the present invention, a third torquetransmitting mechanism is provided that is selectively engageable tointerconnect the common member of the stacked planetary gear setarrangement with the input member.

In still another embodiment of the present invention, a fourth torquetransmitting mechanism is provided that is selectively engageable tointerconnect the sun gear of the stacked planetary gear set arrangementwith the stationary member.

In another embodiment of the present invention, a fifth torquetransmitting mechanism is provided that is selectively engageable tointerconnect the ring gear member of the stacked planetary gear setarrangement with the stationary member.

In another embodiment of the present invention, a sixth torquetransmitting mechanism is provided that is selectively engageable tointerconnect the sun gear of the second planetary gear set with thestationary member.

In still another embodiment of the present invention, the torquetransmitting mechanisms are selectively engageable in combinations of atleast three to establish at least eight forward speed ratios and atleast one reverse speed ratio between the input member and the outputmember.

Further features, aspects and advantages of the present invention willbecome apparent by reference to the following description and appendeddrawings wherein like reference numbers refer to the same component,element or feature.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a lever diagram of an embodiment of a nine speed transmissionaccording to the present invention;

FIG. 2 is a diagrammatic illustration of an embodiment of a nine speedtransmission according to the present invention;

FIG. 3 is a diagrammatic illustration of another embodiment of a ninespeed transmission according to the present invention;

FIG. 4 is a diagrammatic illustration of another embodiment of a ninespeed transmission according to the present invention; and

FIG. 5 is a diagrammatic illustration of another embodiment of a ninespeed transmission according to the present invention;

FIG. 6 is a truth table presenting the state of engagement of thevarious torque transmitting elements in each of the available forwardand reverse speeds or gear ratios of the transmission illustrated inFIGS. 2 and 4.

FIG. 7 is a truth table presenting the state of engagement of thevarious torque transmitting elements in each of the available forwardand reverse speeds or gear ratios of the transmission illustrated inFIGS. 3 and 5.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

Referring now to FIG. 1, an embodiment of a nine or more speedtransmission 10 is illustrated in a lever diagram format. A leverdiagram is a schematic representation of the components of a mechanicaldevice such as an automatic transmission. Each individual leverrepresents a planetary gear set wherein the three basic mechanicalcomponents of the planetary gear are each represented by a node.Therefore, a single lever contains three nodes: one for the sun gear,one for the planet gear carrier, and one for the ring gear. In somecases, two levers may be combined into a single lever having more thanthree nodes (typically four nodes). For example, if two nodes on twodifferent levers are interconnected through a fixed connection they maybe represented as a single node on a single lever. The relative lengthbetween the nodes of each lever can be used to represent the ring-to-sunratio of each respective gear set. These lever ratios, in turn, are usedto vary the gear ratios of the transmission in order to achieve anappropriate ratios and ratio progression. Mechanical couplings orinterconnections between the nodes of the various planetary gear setsare illustrated by thin, horizontal lines and torque transmittingdevices such as clutches and brakes are presented as interleavedfingers. Further explanation of the format, purpose and use of leverdiagrams can be found in SAE Paper 810102, “The Lever Analogy: A NewTool in Transmission Analysis” by Benford and Leising which is herebyfully incorporated by reference.

The transmission 10 includes an input shaft or member 12, a firstplanetary gear set 14, a second planetary gear set 16, a third planetarygear set 18, a fourth planetary gear set 20 and an output shaft ormember 22. The lever of the first planetary gear set 14 has three nodes:a first node 14A, a second node 14B and a third node 14C. The lever ofthe second planetary gear set 16 has three nodes: a first node 16A, asecond node 16B and a third node 16C. The lever of the third planetarygear set 18 has three nodes: a first node 18A, a second node 18B and athird node 18C. The lever of the fourth planetary gear set 20 has threenodes: a first node 20A, a second node 20B and a third node 20C.

The output member 22 is continuously coupled to the first node 14A ofthe first planetary gear set 14 and to the second node 16B of the secondplanetary gear set 16. The first node 14A of the first planetary gearset 14 is coupled to the second node 16B of the second planetary gearset 16. The second node 14B of the first planetary gear set 14 iscoupled to the third node 16C of the second planetary gear set 16. Thethird node 14C of the first planetary gear set 14 is coupled to thesecond node 20B of the fourth planetary gear set 20 and to the secondnode 18B of the third planetary gear set 18. The second node 18B of thethird planetary gear set 18 is coupled to the second node 20B of thefourth planetary gear set 20. The third node 18C of the third planetarygear set 18 is coupled to the third node 20C of the fourth planetarygear set 20.

A first clutch 26 selectively connects the second node 14B of the firstplanetary gear set 14 and the third node 16C of the second planetarygear set 16 with the input member or shaft 12. A second clutch 28selectively connects the first node 18A of the third planetary gear set18 with the input member or shaft 12. A third clutch 30 selectivelyconnects the third node 18C of the third planetary gear set 18 and thethird node 20C of the fourth planetary gear set 20 with the input memberor shaft 12. A first brake 32 selectively connects the first node 18A ofthe third planetary gear set 18 with a stationary member or transmissionhousing 50. A second brake 34 selectively connects the first node 20A ofthe fourth planetary gear set 20 with the stationary member ortransmission housing 50. A third brake 36 selectively connects the firstnode 16A of the second planetary gear set 16 with the stationary memberor transmission housing 50.

Referring now to FIG. 2, a stick diagram presents a schematic layout ofthe embodiment of the nine speed transmission 10 according to thepresent invention. In FIG. 2, the numbering from the lever diagram ofFIG. 1 is carried over. The clutches and couplings are correspondinglypresented whereas the nodes of the planetary gear sets now appear ascomponents of planetary gear sets such as sun gears, ring gears, planetgears and planet gear carriers.

Planetary gear sets 18 and 20 are planetary gear sets that areconfigured to form a stacked planetary gear set arrangement 21. Stackedplanetary gear set arrangement 21 includes a common member 21A. Commonmember 21A functions as the ring gear member of planetary gear set 18and simultaneously as the sun gear member of planetary gear set 20.Planetary gear set 18 further includes a sun gear member 18A and aplanet gear carrier member 18B that rotatably supports a set of planetgears 18D (only one of which is shown). The sun gear member 18A isconnected for common rotation with a first shaft or interconnectingmember 42 and with a second shaft or interconnecting member 44. The ringgear member or common member 21A is connected for common rotation with athird shaft or interconnecting member 46. The planet carrier member 18Bis connected for common rotation with a fourth shaft or interconnectingmember 48. The planet gears 18D are each configured to intermesh withboth sun gear member 18A and ring gear or common member 21A.

In planetary gear set 20, common member 21A functions as the sun gearmember of planetary gear set 20. Planetary gear set 20 further includesa ring gear member 20A and a planet gear carrier member 20B thatrotatably supports a set of planet gears 20D (only one of which isshown). As stated above with respect to planetary gear set 18, commonmember 21A is connected for common rotation with the third shaft orinterconnecting member 46. The ring gear member 20A is connected forcommon rotation with the second brake 34. The planet carrier member 20Bis connected for common rotation with a fourth shaft or interconnectingmember 48 and with a fifth shaft or interconnecting member 52. Theplanet gears 20D are each configured to intermesh with both sun gearmember or common member 21A and ring gear member 20A. Of course, thepresent invention contemplates that the carrier members 18B and 20B ofplanetary gear sets 18 and 20 may be combined to form a single carriermember.

The planetary gear set 14 includes a sun gear member 14C, a ring gearmember 14B and a planet gear carrier member 14A that rotatably supportsa first set of planet gears 14D (only one of which is shown) and asecond set of planet gears 14E (only one of which is shown). The sungear member 14C is connected for common rotation with the fifth shaft orinterconnecting member 52. The ring gear member 14B is connected forcommon rotation with the sixth shaft or interconnecting member 54 andwith the seventh shaft or interconnecting member 56. The planet carriermember 14A is connected for common rotation with an eighth shaft orinterconnecting member 58. The first set of planet gears 14D are eachconfigured to intermesh with both the sun gear member 14C and the secondset of planet gears 14E. The second set of planet gears 14E are eachconfigured to intermesh with both the ring gear member 14B and the firstset of planet gears 14D.

The planetary gear set 16 includes a sun gear member 16A, a ring gearmember 16C and a planet gear carrier member 16B that rotatably supportsa set of planet gears 16D (only one of which is shown). The sun gearmember 16A is connected for common rotation with a ninth shaft orinterconnecting member 60. The ring gear member 16C is connected forcommon rotation with the sixth shaft or interconnecting member 54. Theplanet carrier member 16B is connected for common rotation with theeighth shaft or interconnecting member 58 and with output member orshaft 22. The planet gears 16D are each configured to intermesh withboth the sun gear member 16A and the ring gear member 16C.

The input shaft or member 12 is continuously connected to an engine (notshown) or to a turbine of a torque converter (not shown). The outputshaft or member 22 is continuously connected with the final drive unitor transfer case (not shown).

The torque-transmitting mechanisms or clutches 26, 28, 30 and brakes 32,34 and 36 allow for selective interconnection of the shafts orinterconnecting members, members of the planetary gear sets and thetransmission housing. For example, the first clutch 26 is selectivelyengageable to connect the seventh shaft or interconnecting member 56with the input shaft or member 12. The second clutch 28 is selectivelyengageable to connect the second shaft or interconnecting member 44 withthe input shaft or member 12. The third clutch 30 is selectivelyengageable to connect the second shaft or interconnecting member 46 withthe input shaft or member 12. The first brake 32 is selectivelyengageable to connect the first shaft or interconnecting member 42 withthe stationary element or the transmission housing 50 in order torestrict the member 42 from rotating relative to the transmissionhousing 50. The second brake 34 is selectively engageable to connect thering member 20A with the stationary element or the transmission housing50 in order to restrict the member 20A from rotating relative to thetransmission housing 50. The third brake 36 is selectively engageable toconnect the ninth shaft or interconnecting member 60 with the stationaryelement or the transmission housing 50 in order to restrict the member60 from rotating relative to the transmission housing 50.

In another embodiment of the present invention, a nine speedtransmission 100 is provided. As shown in FIG. 3, the configuration andarrangement of the stacked planetary gear set 21, the interconnectingmembers or shafts 42, 44, 46, 48, 52, 54, 58 and 60 and the torquetransmitting elements or clutches and brakes 26, 28, 30, 32, 34 and 36remain the same as in the nine speed transmission 10 described above.However, planetary gear set 14 is replaced by planetary gear set 102 andplanetary gear set 16 is replaced by planetary gear set 104. Moreover,shaft or interconnecting member 56 has been reconfigured as shaft orinterconnecting member 56′.

The planetary gear set 102 includes a sun gear member 102A, a ring gearmember 102C and a planet gear carrier member 102B that rotatablysupports a set of planet gears 102D (only one of which is shown). Thesun gear member 102A is connected for common rotation with the fifthshaft or interconnecting member 52. The ring gear member 102C isconnected for common rotation with the sixth shaft or interconnectingmember 54 and with output member or shaft 22. The planet carrier member102B is connected for common rotation with the eighth shaft orinterconnecting member 58 and with the reconfigured seventh shaft orinterconnecting member 56′. The planet gears 102D are each configured tointermesh with both the sun gear member 102A and the ring gear member102C.

Planetary gear set 104 includes a sun gear member 104A, a ring gearmember 104C and a planet gear carrier member 104B that rotatablysupports a first set of planet gears 104D (only one of which is shown)and a second set of planet gears 104E (only one of which is shown). Thesun gear member 104A is connected for common rotation with the ninthshaft or interconnecting member 60. The ring gear member 104C isconnected for common rotation with the sixth shaft or interconnectingmember 54. The planet carrier member 104B is connected for commonrotation with an eighth shaft or interconnecting member 58. The firstset of planet gears 104D are each configured to intermesh with both thesun gear member 104A and the second set of planet gears 104E. The secondset of planet gears 104E are each configured to intermesh with both thering gear member 104C and the first set of planet gears 104D.

Moreover, in the instant embodiment the output shaft or member 22 isconnected for common rotation with ring gears 104C and 102C and not tothe carrier member of the second planetary gear set as in the previousembodiment. Further, the first clutch 26 is selectively engageable toconnect the reconfigured seventh shaft or interconnecting member 56′with the input shaft or member 12. As in the previous embodiment, thesecond clutch 28 is selectively engageable to connect the second shaftor interconnecting member 44 with the input shaft or member 12. Thethird clutch 30 is selectively engageable to connect the second shaft orinterconnecting member 46 with the input shaft or member 12. The firstbrake 32 is selectively engageable to connect the first shaft orinterconnecting member 42 with the stationary element or thetransmission housing 50 in order to restrict the member 42 from rotatingrelative to the transmission housing 50. The second brake 34 isselectively engageable to connect the ring member 20A with thestationary element or the transmission housing 50 in order to restrictthe member 20A from rotating relative to the transmission housing 50.The third brake 36 is selectively engageable to connect the ninth shaftor interconnecting member 60 with the stationary element or thetransmission housing 50 in order to restrict the member 60 from rotatingrelative to the transmission housing 50.

In another embodiment of the present invention, a nine speedtransmission 200 is provided. As shown in FIG. 4, the configuration ofthe stacked planetary gear set 21 and planetary gear sets 14 and 16, theinterconnecting members or shafts 42, 44, 46, 48, 52, 54, 56, 58 and 60and the torque transmitting elements or clutches and brakes 26, 28, 30,32, 34 and 36 remain the same as in the nine speed transmission 10described above. However, the relative positioning of the planetary gearsets has changed. The arrangement of the planetary gear sets 14, 16 and21 of transmission 200 is the mirror image of the arrangement of theplanetary gear sets 14, 16 and 21 of transmission 10. The shafts orinterconnecting members have been shortened or lengthened as necessaryto accommodate the new arrangement of the planetary gear sets. Further,shaft 42 is connected to sun gear 18A through shaft 44. Moreover, shaftor interconnecting member 56 connects clutch 26 to ring gear members 14Band 16C. Output member 22 is connected for common rotation with carriermember 16B. Of course, it is within the scope of the invention that anyof the shafts or interconnecting members and planetary gear set membersto which the shafts are connected may be combined to form a unitarymember.

In another embodiment of the present invention, a nine speedtransmission 300 is provided. As shown in FIG. 5, the configuration ofthe stacked planetary gear set 21 and planetary gear sets 102 and 104,the interconnecting members or shafts 42, 44, 46, 48, 52, 54, 58 and 60and the torque transmitting elements or clutches and brakes 26, 28, 30,32, 34 and 36 remain the same as in the nine speed transmission 100described above. However, the relative positioning of the planetary gearsets has changed. The arrangement of the planetary gear sets 102, 104and 21 of transmission 300 is the mirror image of the arrangement of theplanetary gear sets 102, 104 and 21 of transmission 100. The shafts orinterconnecting members have been shortened or lengthened as necessaryto accommodate the new arrangement of the planetary gear sets. Further,shaft 42 is connected to sun gear 18A through shaft 44. Moreover, shaftor interconnecting member 56 now connects clutch 26 to ring gear members102C and 104C. Output member 22 is connected to carrier member 104B. Ofcourse, it is within the scope of the invention that any of the shaftsor interconnecting members and planetary gear set members to which theshafts are connected may be combined to form a unitary member.

Referring now to FIGS. 2, 4 and FIG. 6, the operation of the embodimentsof the nine speed transmissions 10 and 200 will be described. It will beappreciated that transmissions 10 and 200 are capable of transmittingtorque from the input shaft or member 12 to the output shaft or member22 in at least nine forward speed or torque ratios and at least onereverse speed or torque ratio. Each forward and reverse speed or torqueratio is attained by engagement of one or more of thetorque-transmitting mechanisms (i.e. first clutch 26, second clutch 28,third clutch 30, first brake 32, second brake 34 and third brake 36), aswill be explained below. FIG. 6 is a truth table presenting the variouscombinations of torque-transmitting mechanisms that are activated orengaged to achieve the various gear states. An “X” in the box means thatthe particular clutch or brake is engaged to achieve the desired gearstate. An “0” represents that the particular torque transmitting device(i.e. a brake or clutch) is on or active, but not carrying torque. A “G”represents that a garage shift element has to switch on and carryingtorque when the transmission mode selector or shifter (Park, Reverse,Neutral, Drive or Low gear selector) is moved from reverse to drive andswitch off when shifting back to reverse. Actual numerical gear ratiosof the various gear states are also presented although it should beappreciated that these numerical values are exemplary only and that theymay be adjusted over significant ranges to accommodate variousapplications and operational criteria of the transmissions 10 and 200.An example of the gear ratio steps that may be obtained using theembodiments of the present invention are also shown in FIG. 6. Ofcourse, other gear ratios are achievable depending on the gear diameter,gear teeth count and gear configuration selected.

For example, to establish a reverse gear, second clutch 28 and secondbrake 34 and third brake 36 are engaged or activated. The second clutch28 connects the second shaft or interconnecting member 44 with the inputshaft or member 12. The second brake 34 connects the ring member 20Awith the stationary element or the transmission housing 50 in order torestrict the member 20A from rotating relative to the transmissionhousing 50. The third brake 36 connects the ninth shaft orinterconnecting member 60 with the stationary element or thetransmission housing 50 in order to restrict the member 60 from rotatingrelative to the transmission housing 50. Likewise, the nine forwardratios are achieved through different combinations of clutch and brakeengagement, as shown in FIG. 6.

Referring now to FIG. 7, a truth table is provided that presents thevarious combinations of torque-transmitting mechanisms that areactivated or engaged to achieve the various gear states for nine speedtransmissions 100 and 300 shown in FIGS. 3 and 5. The achievablenumerical gear ratios and gear steps of the various gear states are alsopresented and are different than the other embodiments described.Although it should be appreciated that these numerical values areexemplary only and that they may be adjusted to accommodate variousapplications and operational criteria of the transmissions. The nineforward ratios and one reverse ratio are achieved through differentcombinations of clutch and brake engagement, as described above withrespect to FIG. 6.

It will be appreciated that the foregoing explanation of operation andgear states of the nine speed transmissions 10, 200 and 300 assumes,first of all, that all the clutches not specifically referenced in agiven gear state are inactive or disengaged and, second of all, thatduring gear shifts, i.e., changes of gear state, between at leastadjacent gear states, a clutch engaged or activated in both gear stateswill remain engaged or activated.

The description of the invention is merely exemplary in nature andvariations that do not depart from the essence of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; a firstplanetary gear set having a first, a second and a third member; a secondplanetary gear set having a first, a second and a third member; astacked planetary gear set arrangement having a first member, a secondmember, a third member, a fourth member and a fifth member; a firstinterconnecting member continuously interconnecting the first member ofthe first planetary gear set with the second member of the secondplanetary gear set; a second interconnecting member continuouslyinterconnecting the second member of the first planetary gear set withthe third member of the second planetary gear set; a thirdinterconnecting member continuously interconnecting the third member ofthe first planetary gear set with the fourth member of the stackedplanetary gear set arrangement; a fourth interconnecting membercontinuously interconnecting the second member of the stacked planetarygear set arrangement with the fourth member of the stacked planetarygear set arrangement; and at least six torque transmitting mechanismsselectively engageable to interconnect at least one of the first,second, third, fourth and fifth members of the stacked planetary gearset arrangement and the first, second and third members of the first andsecond planetary gear sets with at least one other of first, second,third, fourth and fifth members of the stacked planetary gear setarrangement, and the first, second and third members of the first andsecond planetary gear sets and a stationary member, and wherein the atleast six torque transmitting mechanisms are selectively engageable incombinations of at least three to establish at least eight forward speedratios and at least one reverse speed ratio between the input member andthe output member.
 2. The transmission of claim 1 wherein a first of theat least six torque transmitting mechanisms is selectively engageable tointerconnect the second member of the first planetary gear set with theinput member.
 3. The transmission of claim 2 wherein a second of the atleast six torque transmitting mechanisms is selectively engageable tointerconnect the first member of the stacked planetary gear setarrangement with the input member.
 4. The transmission of claim 3wherein a third of the at least six torque transmitting mechanisms isselectively engageable to interconnect the fifth member of the stackedplanetary gear set arrangement with the input member.
 5. Thetransmission of claim 4 wherein a fourth of the at least six torquetransmitting mechanisms is selectively engageable to interconnect thefirst member of the stacked planetary gear set arrangement with thestationary member.
 6. The transmission of claim 5 wherein a fifth of theat least six torque transmitting mechanisms is selectively engageable tointerconnect the third member of the stacked planetary gear setarrangement with the stationary member.
 7. The transmission of claim 6wherein a sixth of the at least six torque transmitting mechanisms isselectively engageable to interconnect the first member of the secondplanetary gear set with the stationary member.
 8. The transmission ofclaim 1 wherein three of the at least six torque transmitting mechanismsare brakes for connecting at least one of the members of the stackedplanetary gear set arrangement and first and second planetary gear setsto the stationary member and three of the at least six torquetransmitting mechanisms are clutches for connecting at least one otherof the members of the stacked planetary gear set arrangement and firstand second planetary gear sets to at least one other member of thestacked planetary gear set arrangement and the first and secondplanetary gear sets.
 9. The transmission of claim 1 wherein the thirdmember of the first planetary gear set, the first member of the secondplanetary gear set and the first member of the stacked planetary gearset arrangement are sun gears, the second and fourth members of thestacked planetary gear set arrangement, the first member of the firstplanetary gear set and the second member of the second planetary gearset are carrier members and the second member of the first planetarygear set, the third member of the second planetary gear set and thirdmember of the stacked planetary gear set arrangement are ring gears. 10.The transmission of claim 9 wherein the fifth member of the stackedplanetary gear set arrangement meshes with the a first plurality ofpinion gears rotatably supported by the second member of the stackedplanetary gear set arrangement and with a second plurality of piniongears rotatably supported by the fourth member of the stacked planetarygear set arrangement.
 11. A transmission comprising: an input member; anoutput member; a first planetary gear set having a first, a second and athird member; a second planetary gear set having a first, a second and athird member; a stacked planetary gear set arrangement having a firstmember, a second member, a third member, a fourth member and a fifthmember; a first interconnecting member continuously interconnecting thefirst member of the first planetary gear set with the second member ofthe second planetary gear set; a second interconnecting membercontinuously interconnecting the second member of the first planetarygear set with the third member of the second planetary gear set; a thirdinterconnecting member continuously interconnecting the third member ofthe first planetary gear set with the fourth member of the stackedplanetary gear set arrangement; a fourth interconnecting membercontinuously interconnecting the second member of the stacked planetarygear set arrangement with the fourth member of the stacked planetarygear set arrangement; a first torque transmitting mechanism selectivelyengageable to interconnect the second member of the first planetary gearset with the input member; a second torque transmitting mechanismselectively engageable to interconnect the first member of the stackedplanetary gear set arrangement with the input member; a third torquetransmitting mechanism selectively engageable to interconnect the fifthmember of the stacked planetary gear set arrangement with the inputmember; a fourth torque transmitting mechanism selectively engageable tointerconnect the first member of the stacked planetary gear setarrangement with the stationary member; a fifth torque transmittingmechanism selectively engageable to interconnect the third member of thestacked planetary gear set arrangement with the stationary member; and asixth torque transmitting mechanism selectively engageable tointerconnect the first member of the second planetary gear set with thestationary member, and wherein the torque transmitting mechanisms areselectively engageable in combinations of at least three to establish atleast eight forward speed ratios and at least one reverse speed ratiobetween the input member and the output member.
 12. The transmission ofclaim 11 wherein the third member of the first planetary gear set, thefirst member of the second planetary gear set and the first member ofthe stacked planetary gear set arrangement are sun gears, the second andfourth members of the stacked planetary gear set arrangement, the firstmember of the first planetary gear set and the second member of thesecond planetary gear set are carrier members and the second member ofthe first planetary gear set, the third member of the second planetarygear set and third member of the stacked planetary gear set arrangementare ring gears.
 13. The transmission of claim 11 wherein the fifthmember of the stacked planetary gear set arrangement meshes with the afirst plurality of pinion gears rotatably supported by the second memberof the stacked planetary gear set arrangement and with a secondplurality of pinion gears rotatably supported by the fourth member ofthe stacked planetary gear set arrangement.
 14. A transmissioncomprising: an input shaft; a first planetary gear set having a sungear, a carrier member for rotatably supporting a first plurality ofpinion gears and a second plurality of pinion gears and a ring gear; asecond planetary gear set having a sun gear, a carrier member and a ringgear; an output shaft continuously interconnected for common rotationwith the carrier member of the second planetary gear set; a stackedplanetary gear set arrangement having a sun gear, a first carrier memberfor rotatably supporting a first plurality of pinion gears, a secondcarrier member for rotatably supporting a second plurality of piniongears, a ring gear and a common member; a first interconnecting membercontinuously interconnecting the carrier member of the first planetarygear set with the carrier member of the second planetary gear set; asecond interconnecting member continuously interconnecting the ring gearof the first planetary gear set with the ring gear of the secondplanetary gear set; a third interconnecting member continuouslyinterconnecting the sun gear of the first planetary gear set with thesecond carrier member of the stacked planetary gear set arrangement; afourth interconnecting member continuously interconnecting the firstcarrier member of the stacked planetary gear set arrangement with thesecond carrier member of the stacked planetary gear set arrangement; afirst torque transmitting mechanism selectively engageable tointerconnect the ring gear of the first planetary gear set with theinput member; a second torque transmitting mechanism selectivelyengageable to interconnect the sun gear of the stacked planetary gearset arrangement with the input member; a third torque transmittingmechanism selectively engageable to interconnect the common member ofthe stacked planetary gear set arrangement with the input member; afourth torque transmitting mechanism selectively engageable tointerconnect the sun gear of the stacked planetary gear set arrangementwith the stationary member; a fifth torque transmitting mechanismselectively engageable to interconnect the ring gear member of thestacked planetary gear set arrangement with the stationary member; and asixth torque transmitting mechanism selectively engageable tointerconnect the sun gear of the second planetary gear set with thestationary member, and wherein the torque transmitting mechanisms areselectively engageable in combinations of at least three to establish atleast eight forward speed ratios and at least one reverse speed ratiobetween the input member and the output member.
 15. The transmission ofclaim 14 wherein the common member of the stacked planetary gear setarrangement meshes with the first plurality of pinion gears rotatablysupported by the first carrier member of the stacked planetary gear setarrangement and with the second plurality of pinion gears rotatablysupported by the second carrier member of the stacked planetary gear setarrangement.
 16. A transmission comprising: an input shaft; a firstplanetary gear set having a sun gear, a carrier member and a ring gear;an output shaft continuously interconnected for common rotation with thering gear of the first planetary gear set; a second planetary gear sethaving a sun gear, a carrier member for rotatably supporting a firstplurality of pinion gears and a second plurality of pinion gears and aring gear; a stacked planetary gear set arrangement having a sun gear, afirst carrier member for rotatably supporting a first plurality ofpinion gears, a second carrier member for rotatably supporting a secondplurality of pinion gears, a ring gear and a common member; a firstinterconnecting member continuously interconnecting the carrier memberof the first planetary gear set with the carrier member of the secondplanetary gear set; a second interconnecting member continuouslyinterconnecting the ring gear of the first planetary gear set with thering gear of the second planetary gear set; a third interconnectingmember continuously interconnecting the sun gear of the first planetarygear set with the second carrier member of the stacked planetary gearset arrangement; a fourth interconnecting member continuouslyinterconnecting the first carrier member of the stacked planetary gearset arrangement with the second carrier member of the stacked planetarygear set arrangement; a first torque transmitting mechanism selectivelyengageable to interconnect the carrier member of the first planetarygear set with the input member; a second torque transmitting mechanismselectively engageable to interconnect the sun gear of the stackedplanetary gear set arrangement with the input member; a third torquetransmitting mechanism selectively engageable to interconnect the commonmember of the stacked planetary gear set arrangement with the inputmember; a fourth torque transmitting mechanism selectively engageable tointerconnect the sun gear of the stacked planetary gear set arrangementwith the stationary member; a fifth torque transmitting mechanismselectively engageable to interconnect the ring gear member of thestacked planetary gear set arrangement with the stationary member; and asixth torque transmitting mechanism selectively engageable tointerconnect the sun gear of the second planetary gear set with thestationary member, and wherein the torque transmitting mechanisms areselectively engageable in combinations of at least three to establish atleast eight forward speed ratios and at least one reverse speed ratiobetween the input member and the output member.
 17. The transmission ofclaim 16 wherein the common member of the stacked planetary gear setarrangement meshes with the first plurality of pinion gears rotatablysupported by the first carrier member of the stacked planetary gear setarrangement and with the second plurality of pinion gears rotatablysupported by the second carrier member of the stacked planetary gear setarrangement.
 18. A transmission comprising: an input shaft; a firstplanetary gear set having a sun gear, a carrier member and a ring gear;a second planetary gear set having a sun gear, a carrier member forrotatably supporting a first plurality of pinion gears and a secondplurality of pinion gears and a ring gear; an output shaft continuouslyinterconnected for common rotation with the carrier member of the secondplanetary gear set; a stacked planetary gear set arrangement having asun gear, a first carrier member for rotatably supporting a firstplurality of pinion gears, a second carrier member for rotatablysupporting a second plurality of pinion gears, a ring gear and a commonmember; a first interconnecting member continuously interconnecting thecarrier member of the first planetary gear set with the carrier memberof the second planetary gear set; a second interconnecting membercontinuously interconnecting the ring gear of the first planetary gearset with the ring gear of the second planetary gear set; a thirdinterconnecting member continuously interconnecting the sun gear of thefirst planetary gear set with the second carrier member of the stackedplanetary gear set arrangement; a fourth interconnecting membercontinuously interconnecting the first carrier member of the stackedplanetary gear set arrangement with the second carrier member of thestacked planetary gear set arrangement; a first torque transmittingmechanism selectively engageable to interconnect the ring gear of thefirst planetary gear set with the input member; a second torquetransmitting mechanism selectively engageable to interconnect the sungear of the stacked planetary gear set arrangement with the inputmember; a third torque transmitting mechanism selectively engageable tointerconnect the common member of the stacked planetary gear setarrangement with the input member; a fourth torque transmittingmechanism selectively engageable to interconnect the sun gear of thestacked planetary gear set arrangement with the stationary member; afifth torque transmitting mechanism selectively engageable tointerconnect the ring gear member of the stacked planetary gear setarrangement with the stationary member; and a sixth torque transmittingmechanism selectively engageable to interconnect the sun gear of thesecond planetary gear set with the stationary member, and wherein thetorque transmitting mechanisms are selectively engageable incombinations of at least three to establish at least eight forward speedratios and at least one reverse speed ratio between the input member andthe output member.
 18. The transmission of claim 17 wherein the commonmember of the stacked planetary gear set arrangement meshes with thefirst plurality of pinion gears rotatably supported by the first carriermember of the stacked planetary gear set arrangement and with the secondplurality of pinion gears rotatably supported by the second carriermember of the stacked planetary gear set arrangement.